Through a narrow gorge, it emerges into view, revealing awe-inspiring monuments cut into the surrounding rose sandstone cliffs long ago. There are many ways to get into Petra, but none of them is easy, and if the valleys are blocked off, it is almost impossible for anyone to enter.
The main entrance to Petra, called the Siq, is a very narrow gorge, with sides as high as 200 meters.
A handful of people on them could hold off an entire army.